Chelolliall COllserwuioll (lnd Biology, 1996,2(2):230- 236 © 1996 by Chelonian Research Foundation Reproductive Physiology of Nesting Leatherback Turtles (Dermochelys coriacea) at Las Baulas National Park, Costa Rica i 2 3 4 DAVID C. ROSTAL , FRANK V. PALADIN0 , RHONDA M. PATTERSON , AND JAMES R. SPOTILA I Department of Biology, Georgia Southern Uni versity, Statesboro, Georgia 30460 USA [Fax: 912-681-0845; E-mail:
[email protected]}; 2Department of Biology, Indiana-Purdue University, Fort Wayne, Indiana 46805 USA ; 3Department of Biology, Texas A&M University, College Station, Texas 77843 USA ; 4Department o{Bioscience and Biotechnology, Drexel University, Philadelphia, Pennsylvania 19104 USA ABSTRACT. - The reproductive physiology of nesting leatherback turtles (Dermochelys coriacea) was studied at Playa Grande, Costa Rica, from 1992 to 1994 during November, December, and January. Ultrasonography indicated that 82 % of nesting females had mature preovulatory ovaries in November, 40 % in December, and 23 % in January. Mean follicular diameter was 3.33 ±0.02 cm and did not vary significantly through the nesting season. Plasma testosterone and estradiol levels measured by radioimmunoassay correlated strongly with reproductive condition. No correlation, however, was observed between reproductive condition and plasma progesterone levels. Testoster one declined from 2245 ± 280 pglml at the beginning of the nesting cycle to 318 ± 89 pglml at the end of the nesting cycle. Estradiol declined in a similar manner. Plasma calcium levels were constant throughout the nesting cycle. Vitellogenesis appeared complete prior to the arrival of the female at the nesting beach. Dermochelys coriacea is a seasonal nester displaying unique variations (e.g., 9 to 10 day internesting interval, yolkless eggs) on the basic chelonian pattern.